Inactivated vaccine-elicited potent antibodies can broadly neutralize SARS-CoV-2 circulating variants.

A full understanding of the inactivated COVID-19 vaccine-mediated antibody responses to SARS-CoV-2 circulating variants will inform vaccine effectiveness and vaccination development strategies. Here, we offer insights into the inactivated vaccine-induced antibody responses after prime-boost vaccination at both the polyclonal and monoclonal levels. We characterized the VDJ sequence of 118 monoclonal antibodies (mAbs) and found that 20 neutralizing mAbs showed varied potency and breadth against a range of variants including XBB.1.5, BQ.1.1, and BN.1. Bispecific antibodies (bsAbs) based on nonoverlapping mAbs exhibited enhanced neutralizing potency and breadth against the most antibody-evasive strains, such as XBB.1.5, BQ.1.1, and BN.1. The passive transfer of mAbs or their bsAb effectively protected female hACE2 transgenic mice from challenge with an infectious Delta or Omicron BA.2 variant. The neutralization mechanisms of these antibodies were determined by structural characterization. Overall, a broad spectrum of potent and distinct neutralizing antibodies can be induced in individuals immunized with the SARS-CoV-2 inactivated vaccine BBIBP-CorV, suggesting the application potential of inactivated vaccines and these antibodies for preventing infection by SARS-CoV-2 circulating variants.

Fatal multisystem inflammatory syndrome in a 78-year-old adult after severe COVID-19 pneumonia during 2022 Omicron variant epidemic in Shanghai, China.

Multisystem inflammatory syndrome adult type (MIS-A) is a rare type of post-acute COVID-19 syndrome which more frequently occurred in younger population. Here we present a 78-year-old Chinese female, the oldest case reported, diagnosed with MIS-A who had severe SARS-CoV-2 infection. She was diagnosed with severe COVID-19 and experienced an unexpected sudden hemodynamic collapse in the recovery period within three weeks. Her platelet count was sharply dropped, accompanied with sustained cardiac, kidney and liver injury. She was diagnosed with MIS-A according to criteria established by Center of Disease Control and Prevention. Though her condition was improved under administrating with high dose of methylprednisolone and intravenous immunoglobulin, methylprednisolone was unable to withdraw till two weeks as her partial pressure of oxygen/fraction of inspiration oxygen ratio and platelet count dropped on the heels of decreasing dosage. Unfortunately, the patient's condition gradually deteriorated with the development of severe nosocomial pneumonia. We presented this rare case in order to emphasize that MIS-A could occur in the elderly and the management of this population might be more difficult as the condition of the elderly with SARS-CoV-2 infection and MIS-A might be more severe.